Dielectric motor

ABSTRACT

A motor whose torque is not generated by magnetic fields but rather by dielectric forces to be used in microelectronics and micromechanics. The rotors are composed of several dielectrics, which are arranged in a sector-shaped or shell-shaped manner or partially or completely envelop each other. These motors can be miniaturized down to a size of a few millimeters. They are distinguished by having slow to medium rotation speeds, short starting phases (ms range and less), extremely low current consumption, simple construction, high running constancy and being practically maintenance free. The characteristic curve of rotation (rotation as the function of the field frequency) may be selected in many ranges by changing the dielectrics of the rotor.

FIELD OF THE INVENTION

The fields of the present invention are, e.g. microelectronics, in whichminiaturized dielectric motors can find application as micromechanicaldrive, control, switch and sensor systems. They may, however, also beutilized as miniature motors in micro-surgery, chemistry and genetechnology.

BACKGROUND OF THE INVENTION

Dielectric motors have been known for quite some time, were however notemployed in practice due to their grave drawbacks (very small torque, nofixed sense of rotation. A description of the theory of dielectricmotors goes back to Heinrich Hertz, Hertz, Wied. Anm 13 (1881) 266/.

There are motors known whose rotors are composed of a dielectric and aresupported between two or more electrodes. The electrodes are triggeredwith constant voltages. The rotation of the rotors ensues eitherfollowing mechanical turning or via auxilliary electrodes, which, e.g.induce the solution enveloping the rotor to flow, thereby turning therotor, QUINCKE, Wied. Anm. 59 (1896) 417; SECKER and SCIALOM, J. Appl.Physics 39 (1968) 277, SECKER and BELMONT, J.Phys.D: Appl. Phys. 3(1970) 216. The rotor is usually enveloped by a gaseous or fluid mediumor is in a vacuum; /QUINCKE, Wied. Anm. 59 (1896) 417.

The disadvantage of these motors is, apart from the rotation directionnot being fixed and the required auxilliary start devices, the difficultregulation of the rotation speed, as it is very dependent on the squareof the field strength. Recently, it has been recognized that the extrememiniaturizability of this type of motor is an advantage andmicromechanical components in the form of chips have been developed (GEO10 (1988) 188; U.S. Pat. No. 4,740,410) in which rotating electricfields produced via multi-electrode systems were utilized so that startdevices can be obviated.

Rotating electric fields have been used to examine biological objectssuch as cells since 1982 (ARNOLD and ZIMMERMANN, Z.Naturforsch. 37c(1982) 908), are however, also employed in conventional motors of themagnetic induction principle.

An object of the present invention is to provide a cost-effectiveimproved dielectric motor which allow additional possible applicationsas an integral component in microelectronics and in micromechanics.

Another object of the present invention is to provide a dielectric motorwith an influenceable characteristic rotation curve, having constant andvariable rotation conditions that can be easily and precisely controlledas well as universally and cost-efficiently utilized. The startingperiod should lie in the millisecond range and below.

In accordance with the present invention, this object is accomplished inthat the rotor has in one or several directions continuous ordiscontinuous transitions between different dielectric materials. Therotor may be composed of symmetric or asymmetric sectors which arearranged radially to the axis of rotation. A rotor configuration inwhich the rotor comprises symmetric or asymmetric layers, which arearranged radially or axially to the axis of rotation, is alsocontemplated. Electric conductors or a vacuum may be disposed betweenthe layers and the sectors. Furthermore, combinations of sectors andradial and axial layers may be used in the design of the construction ofthe dielectric rotor.

The present invention also permits a combination of homogeneous andinhomogeneous dielectrics, which are optically transparent and/ordeformable. The rotors are driven via circular polarized ordiscontinuously rotating electric fields, by which the rotationdirection is determined.

With increasing number of rotor dielectrics, the rotation spectrum(rotation as the function of the circular frequency of the externalfield) of the rotor becomes more complicated and is characterized by amultiplicity of well-differentiable states. These surprising rotationspectra are not known from any other type of motor.

In miniaturized form, the starting time of the motor is less than 1 ms,which proves its advantages for microelectronic applications. Theprinciple described herein differs fundamentally from induction fieldmotors. In many ranges the characteristic rotation curve of the motorcan be selected freely via the selection and combination of the rotordielectrics.

Other objects, advantages and novel features of the present inventionwill become apparent from the following detailed description of theinvention when considered in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1a and 1b show a rotor having two dielectrics constructed inaccordance with an embodiment of the present invention andcharacteristic rotation curve for the rotor.

FIGS. 2a and 2b show a rotor having dielectric sectors constructed inaccordance with another embodiment of the present invention and acharacteristic rotation curve for the rotor.

FIGS. 3a and 3b show a rotor having axially arranged dielectric disksconstructed in accordance with another embodiment of the presentinvention and a characteristic rotation curve for the rotor.

DETAILED DESCRIPTION OF THE DRAWINGS

The rotor of FIG. 1a comprises two dielectrics 2a, 2b and is envelopedby an enveloping medium such as a low conductive fluid 5 (water,alcohol, etc.). The external electric field generated by at least threeelectrodes acts via the enveloping medium 5. The electrodes, an electriccircuit that triggers and controls the dielectric motor, and a substratein which the electric circuit is integrated, are illustratedschematically in FIG. 1a. The substrate can be made of a semi-conductingmonocrystal, for example. The rotor is supported in a known manner bysupport 6, 1 designating the axis of rotation. The circular frequency(f) of the field and the field strength (usually 5 to 100 kV/m)determines the rotation speed of the rotor. The characteristic curve ofthe rotor (rotation as a function of the circular frequency of theexternal field) may be fixed and altered by the selection andcombination of the dielectrics of the rotor and the enveloping solution5. A possible characteristic rotation curve is given in FIG. 1b. Eachdielectric can be chacterized by the relaxation period of the respectivepolarization charges. This period is dependent on the electricproperties of the respective adjacent dielectrics intersected by thefield lines. In order to describe the parameters of the curve, thethickness of the dielectrics and their relaxation period are given inthe following.

Contemplated Parameters for the embodiment of FIG. 1a:

    ______________________________________                                                        Relaxation period in s.sup.-1                                 d1 in m  d2 in m      t1        t2                                            ______________________________________                                        4.8*10.sup.-6                                                                          2*10.sup.-7  1.6*10.sup.-6                                                                           2.3*10.sup.-3                                 ______________________________________                                    

The rotor of FIG. 2a has six sectors 3a, 3b, 3c, 3d, 3e and 3f and isenveloped by a low-conductive fluid 5 (water, alcohol, etc. ). Theelectric properties of the rotor and its surroundings determine thecharacteristic rotation curve. The turn of the rotor can be induced fromthe outside via a rotating electric field without loops. The torque canbe influenced via the field strength or the circular frequency of thefield. The characteristic rotation curves can be fixed and altered viathe combination of the sector dielectrics. A possible characteristiccurve is given in FIG. 2a.

The widths of the sectors b1-b6 (FIG. 2a) are distributed in the examplein fractions of the circumference (U) of the rotor as follows:

b1=b4=0.15

b2=b5=0.15

b3=b6=0.2

The relaxation periods of the dielectrics for FIG. 2a are approx:

t1=t4=10⁻³ s⁻¹

t2=t5=10⁻⁵ s⁻¹

t3=t6=10⁻⁴ s⁻¹

The rotor shown in FIG. 3a has three axially arranged dielectric layers4a, 4b and 4c. A possible characteristic curve is given in FIG. 3A. Itis based on the following set of parameters:

H1=H2=H3

t1=10⁻³ s⁻¹

t2=10⁻³ s⁻¹

t3=10⁻⁷ s⁻¹

The dielectric elements of the motor are made using manufacturingmethods common in semiconductor technology and micromechanics.

By way of example silicon, possibly provided with thin insulation layerssuch as SiP₂ or Si₃ N₄, or glass is used as a substrate.

The electrodes are structured using photolithographic methods andgalvanically molded, e.g. with gold. In this way the pattern of theelectrodes can be defined with micrometer precision. By using deep-etchlithography electrode heights of several hundred micrometers can beobtained.

The rotor is made of dielectric materials also using micro-mechanicalprocesses. Layers such as SiO₂, Si₃ N₄ or TiO₂ can be made andstructured up to thicknesses in the micro-meter range. Thicker rotorscan be made of photographic lacquer using deep lithography.

Precise grooves and channels, which serve to fix the rotor or to conductto or away the solution or medium enveloping the motor, are etched intothe substrate with isotropic or anisotropic and selective etchingprocesses. With the same processes, a rotor axis can also be made whichis connected to the substrate.

An encapsulation of the system can be obtained with a second wafer whichis bonded onto the substrate wafer.

The use of silicon as a substrate material offers the specialpossibility of integrating electric circuits for triggering andcontrolling the motor together with the mechanical elements on onecommon substrate (wafer).

Although the invention has been described and illustrated in detail, itis to be clearly understood that the same is by way of illustration andexample, and is not to be taken by way of limitation. The spirit andscope of the present invention are to be limited only by the terms ofthe appended claims.

What is claimed is:
 1. A dielectric motor in an enveloping medium,comprising:electrodes; and a rotor having a plurality of dielectrics andin at least one direction continuous transitions between the dielectricswith one of electrically conductive zones and a vacuum between saiddielectrics; wherein the rotor is driven by one of circular polarizedand discontinuously rotating electrical fields, and has a rotationspectrum with a plurality of differentiable states.
 2. The dielectricmotor of claim 1, wherein the dielectrics are arranged radially to anaxis of rotation in one of symmetric and asymmetric layers.
 3. Thedielectric motor of claim 1, wherein the dielectrics are arrangedradially to an axis of rotation in one of symmetric and asymmetricdielectric sectors.
 4. The dielectric motor of claim 1, wherein thedielectrics are arranged axially to an axis of rotation in one ofsymmetric and asymmetric layers.
 5. A dielectric motor according toclaim 4, wherein said dielectric layers are arranged along said axis ofrotation.
 6. A dielectric motor according to claim 3, wherein saiddielectric sectors are arranged around said axis of rotation.
 7. Adielectric motor according to claim 2, wherein said dielectric layersare arranged around said axis of rotation.
 8. A dielectric motoraccording to claim 1, wherein said dielectrics at least partially coverone another.
 9. A dielectric motor according to claim 1, wherein saiddielectrics are homogeneous.
 10. A dielectric motor according to claim1, wherein said dielectrics are inhomogeneous.
 11. A dielectric motoraccording to claim 1, wherein at least one of said dielectrics ispenetrable for electromagnetic waves.
 12. A dielectric motor accordingto claim 1, wherein at least one of said dielectrics is deformable. 13.A dielectric motor according to claim 1, wherein at least one of SiO₂,Si₃ N₄, TiO₂ or glass is used as said dielectrics and said electrodesare photolithographically galvanically molded electrodes.
 14. Adielectric motor according to claim 1, further comprising an electriccircuit for triggering and controlling said dielectric motor, saidelectric circuit and said monitor being integrated into a substrate. 15.A dielectric motor according to claim 14, wherein said substrate is madeof a semiconducting monocrystal.
 16. A dielectric motor according toclaim 1, wherein said dielectrics at least partially cover theelectrically conductive zones.
 17. A dielectric motor in an envelopingmedium, comprising:electrodes; and a rotor having a plurality ofdielectrics and in at least one direction continuous transitions betweenthe dielectrics with one of electrically conductive zones and a vacuumbetween said dielectrics; wherein the rotor is driven via rotatingelectrical fields such that a characteristic curve of the rotor has amultiplicity of well-defined states, said states being alterable viaselections of the plurality of dielectrics of the rotor.